Thienamycin having a carbapenem skelton has been regarded as a promising new antibiotic since its discovery in 1976, because it is effective upon bacterial strains which are resistant against prior art antibiotics and it can exhibit excellent antibacterial activity.
However, thienamycin and various other carbapenem derivatives reported thereafter have to be used as a mixed preparation with a dehydropeptidase (DHP) inhibitor, because they are not only physico-chemically unstable but also apt to be decomposed by DHP and the like enzyme in the kidney, thereby causing side-effects such as renal toxicity.
In addition, an unexamined published Japanese Patent application No. JP-A-60-233076 discloses 1-.beta.-methylcarbapenem compounds which are stable against .beta.-lactamase producing strains, have physico-chemically stable nature and exhibit strong antibacterial activity. These compounds, however, are still unsatisfactory in terms of their stability against DHP and antibacterial activity.
The inventors of the present invention have conducted intensive studies with the aim of finding a carbapenem derivative having more excellent properties and, as a result, have accomplished the present invention by finding a compound which is effective upon various bacterial strains including Pseudomonas aeruginosa, excellent in terms of safety and stability against hydrolases such as DHP and the like.